Bipolar Conducting Polymer Crawlers Based on Triple Symmetry Breaking

International audienc

Wireless Electromechanical Readout of Chemical Information

International audienceCollecting electrochemical information concerning the presence of molecules in a solution is usually achieved by measuring current, potential, resistance or impedance via connection to a power supply. Here, we suggest wireless electromechani-cal actuation as a straightforward readout of chemical information. This can be achieved based on the concept of bipolar electro-chemistry, which allows measuring the presence of different model species in a quantitative way. We validate the concept by using a free-standing polypyrrole film. Its positively polarized extremity participates in an oxidation of the analyte and delivers electrons to the opposite extremity for the reduction of the polymer. This reduction is accompanied by the insertion of counter ions and thus leads to partial swelling of the film, inducing its bending. The resulting actuation is found to be a linear function of the analyte concentration and also a Michaelis-Menten type correlation is obtained for biochemical analytes. This electromechanical transduc-tion allows an easy optical readout and opens up very interesting perspectives not only in the field of sensing, but also far beyond, such as for the elaboration of self-regulating biomimetic systems

Wireless Coupling of Conducting Polymer Actuators with Light Emission

International audienceCombining the actuation of conducting polymers with additional functionalities is an interesting fundamental scientific challenge and increases their application potential. Here we demonstrate the possibility of direct integration of a miniaturized light emitting diode (LED) in a polypyrrole (PPy) matrix in order to achieve simultaneous wireless actuation and light emission. A light emitting diode is used as a part of an electroactive surface on which electrochemical polymerization allows direct incorporation of the electronic device into the polymer. The resulting free-standing polymer/LED hybrid can be addressed by bipolar electrochemistry to trigger simultaneously oxidation and reduction reactions at its opposite extremities, leading to a controlled deformation and an electron flow through the integrated LED. Such a dual response in the form of actuation and light emission opens up interesting perspectives in the field of microrobotics

pKa tuning in quadrupolar-type two-photon ratiometric fluorescent membrane probes

International audienceTwo bolaamphiphilic quadrupoles built from a fluorene core conjugated with azine endgroups were designed and successfully used to stain GUV membranes. Their quadrupolar character induces both a shift of the pKa values close to the physiological pH and large two-photon absorption responses (i.e. over 1000 GM for acidic forms). As such they hold promise as ratiometric two-photon pH probes for monitoring slight variations of pH near cell membranes using two-photon excitation in the NIR regio

Infrared photoinduced electrochemiluminescence microscopy of single cells

Electrochemiluminescence (ECL) is evolving rapidly from a purely analytical technique into a powerful microscopy. Herein, we report the imaging of single cells by photoinduced ECL (PECL; λem = 620 nm) stimulated by an incident near-infrared light (λexc = 1050 nm). The cells were grown on a metal–insulator–semiconductor (MIS) n-Si/SiOx/Ir photoanode that exhibited stable and bright PECL emission. The large anti-Stokes shift allowed for the recording of well-resolved images of cells with high sensitivity. PECL microscopy is demonstrated at a remarkably low onset potential of 0.8 V; this contrasts with classic ECL, which is blind at this potential. Two imaging modes are reported: (i) photoinduced positive ECL (PECL+), showing the cell membranes labeled with the [Ru(bpy)3]2+ complex; and (ii) photoinduced shadow label-free ECL (PECL−) of cell morphology, with the luminophore in the solution. Finally, by adding a new dimension with the near-infrared light stimulus, PECL microscopy should find promising applications to image and study single photoactive nanoparticles and biological entities

Influence of alkaline modification on adsorption properties of aluminum oxide

In this work the adsorption capacity of samples A-2-9С, A-2-Na-9С, A-2-K-9С was studied. It was found that alkaline modification leads to an increase in the efficiency of aluminum oxide dehydrators

Mécanismes moléculaires impliqués dans la genèse des desminopathies

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Coupling Electrochemistry with Fluorescence Confocal Microscopy to Investigate Electrochemical Reactivity. A Case Study with the Resazurin-Resorufin Fluorogenic Couple

The redox couple resazurin-resorufin exhibits electrofluorochromic properties which are investigated herein by absorption and fluorescence spectroelectrochemistry, and by electrochemically coupled fluorescence confocal laser scanning microscopy (EC-CLSM). At pH 10, the highly fluorescent resorufin dye is generated at the electrode surface by the electrochemical reduction of the poorly fluorescent resazurin. Per-forming EC-CLSM at electrode surfaces allows to monitor spatially resolved electro-chemical processes in situ and in real time. Using a small (315 µm diameter) cylin-drical electrode, a steady-state diffusion layer builds up under potentiostatic conditions at −0.45 V vs. AgSCOPUS: ar.jinfo:eu-repo/semantics/publishe